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TPS92512: Adjust TPS92512 current regulation using IADJ pin

Jimmy Zhou95
Intellectual 870 points
Part Number: TPS92512

Hi,

My customer want to use TPS92512 to adjust current by IADJ pin linearly and put PDIM to high with ISENSE res 0.2R. But they find the output current is not 0 (around 4mA). So I want to check whether this is due to our device limitation or external circuit. Thanks! 

Jimmy

  • 0
    TI__Mastermind 28655 points

    Hello Jimmy,

    The TPS92512 was not intended to dim to zero current.  Datasheet page 11 at the bottom:  "Below 180 mV the TPS92512 dims well but may have more variation between circuits.
    Due to internal offsets pulling IADJ to 0 V will not result in a current sense voltage of 0 V. Some small current will
    continue to run unless the PDIM pin is pulled low or the device is disabled using the UVLO pin."

    Besides the internal offsets the gate drive boot capacitor is charged through the LEDs.  This is not the best part choice to dim to very low dim levels.  Depending on input voltage, output voltage and switching frequency there can be other limitations as well.

    Best Regards,